First on the list, we have Attachment Theory in Practice: Emotionally Focused Therapy (EFT) With Individuals, Couples, and Families, written by leading attachment theory expert and psychologist, Susan M. Johnson. This is one of the books Birkel had to recommend, and it's all about applying attachment theory to therapy for real results.

Attachment Theory in Practice: Emotionally Focused Therapy (EFT) With Individuals, Couples, and Families by Susan M. Johnson, $33

Another one of Birkel's recommendations, The Power of Attachment: How To Create Deep and Lasting Intimate Relationships helps readers explore their earliest years of life, their traumas, and how those things are affecting them today. Poole Heller is another leading attachment theory expert, and with this book having an average rating of 4.8 out of 5 stars, readers have clearly gotten something out of it.

The Power of Attachment: How To Create Deep and Lasting Intimate Relationships by Diane Poole Heller Ph.D., $16.13

If you're looking for more of an interactive way to learn about attachment theory, look no further than The Attachment Theory Workbook: Powerful Tools To Promote Understanding, Increase Stability, and Build Lasting Relationships. This is another one of Birkel's recommendations, and it includes helpful, actionable strategies so you can put your newfound knowledge of attachment theory to work.

The Attachment Theory Workbook: Powerful Tools To Promote Understanding, Increase Stability, and Build Lasting Relationships by Annie Chen, LMFT, $13.79

In Wired for Love: How Understanding Your Partner's Brain and Attachment Style Can Help You Defuse Conflict and Build a Secure Relationship, couples can learn about each other and create rituals to strengthen their relationship. This book combines research on the neuroscience of love, attachment theory, and emotion regulation, and offers detailed ways to improve your connection with your partner and understand each other on a deeper level.

Wired for Love: How Understanding Your Partner's Brain and Attachment Style Can Help You Defuse and Build a Secure Relationship by Stan Tatkin, PsyD, MFT, $17.95

If you're in a polyamorous or ethically non-monogamous relationship, it may be particularly important to understand your own, and your partner's attachment style. In Polysecure: Attachment, Trauma and Consensual Nonmonogamy, psychotherapist Jessica Fern unpacks how to work toward secure attachment when in multiple relationships.

Polysecure: Attachment, Trauma and Consensual Nonmonogamy by Jessica Fern, M.S., $15.31

In Attached: The New Science of Adult Attachment and How It Can Help You Find—and Keep—Love, psychiatrist and neuroscientist Amir Levine, M.D., and psychology expert Rachel Heller, M.A., break down what attachment theory is all about, how to figure out which style you have, and of course, how to work with it. And according to the New York Times, "Over a decade after its publication, one book on dating has people firmly in its grip," and it's this one.

Attached: The New Science of Adult Attachment and How It Can Help You Find—and Keep—Love by Amir Levine, M.D., and Rachel S.F. Heller, M.A., $12.68

And last but not least, we have another book by attachment theory expert Susan M. Johnson, who Birkel highly recommends for anything attachment-related. This is actually a book meant for therapists to use in couples' therapy with clients who have experienced trauma, though non-clinical reviewers say they still got something out of it on their own.

Emotionally Focused Couple Therapy With Trauma Survivors: Strengthening Attachment Bonds by Susan M. Johnson, $32